The invention relates to a process for obtaining juices, oils and cakes, in stable forms, by the pressing of fresh plant products. It also relates to the juices, oils and cakes thus obtained.
The invention relates more particularly to a process which facilitates the extraction and the separation of juices, oils and cakes, and which automatically allows the resulting products of this pressing to be stabilized at the same time.
Although in what follows in the description and in the claims, the invention, most generally, is described with respect to its application to products of plant origin, such as plants, fruits, vegetables or spices, it may also be employed with products of animal origin.
The extraction of juices, oils and cakes is well known, notably in oenology, in the fruit juice industry, in sugar-refining or in oil-mills.
Most generally, the material from which the juices are extracted by pressing is previously crushed. The action of crushing, then pressing breaks open the cells, empties them of their contents (cytoplasm) and drains these contents together with the interstitial water from the product.
The more fluid the cytoplasm, the more abundant the interstitial water and the easier the extraction. Such is the case for raisins, oranges, and the like.
If on the other hand, as is frequently the case, the cytoplasm is more or less viscous because many of its molecules are colloids (proteins, amino acids, gums, pectin, cellulose, and the like) which swell and produce gels which are more or less thick with vacuolar and interstitial water, the extraction is more difficult. This is the case with apples, quinces, sugar-cane, and the like.
The same applies when the cytoplasm contains a lot of fatty substances, particularly emulsified with water. This is the case for olive pulp, coconut pulp, and the like.
One solution to these difficulties consists in "breaking", as best as possible, the gels and emulsions if they are not too abundant--after crushing and before pressing--by carrying out a substantial "trituration", in principle with rotating grinding wheels applies, olives, sugar-cane, and the like.
If these gels and emulsions are held together very tightly and are particularly abudnant in oleaginous products, another solution consists in dehydrating by drying the corresponding products such as coconut which is dried to give copra, peanuts and the like. But in so doing, another disadvantage is met which is even found with naturally drying products peanuts, nuts, and the like, and which results from the fact that the vacuolar and interstitial water is, then, not very abundant, thereby still causing difficulties in extraction. This is resolved by employing very high pressure pressing equipment, named an "expeller", which is very expensive or else by employing solvent extraction techniques which are fairly sophisticated and costly as well. Furthermore, the oils obtained by these processes from often poorly dried products or form solvents must, more ore less necessarily, be "refined", that is to say, be subjected to sophisticated, expensive and very constraining new techniques, therefore to the detriment, a bit more, of their integrity. In this case, as well, the resulting cakes can be used, at best, only as animal feed, as fertilizer or as combustibles.
It should finally be noted that in all cases of extraction, the products obtained are not in stable forms and that they have to be stabilized one way or another: by alcoholic fermentation wines, by pasteurization for fruit juices, by dehydration for oils, cakes and the like. Generally, also, all the products are not recovered, in particular the water in oil-mills.